From data developed within the last 15 years, the aggregate available evidence suggests that insulin dependent diabetes mellitus (IDDM) results from the interplay of genetic predisposition and environmental exposures. This proposal's objective is to test the association of certain environmental factors to the onset of IDDM. A primary aim is to conclusively examine the relationship between group B Coxsackievirus infections and IDDM. Secondly, other environmental factors and/or their correlates (i.e. socioeconomic status, chemical and x-ray exposures, urban-rural residence, immunizations and prior medical history) will be examined. Last, we plan to examine whether genetic patterns, as exemplified by HLA A, B and DR loci typing, are associated with any particular environmental exposure. The study will be a case-control design with newly diagnosed cases of IDDM aged 0-29 years recruited from a 14-county area of southern Wisconsin. Two controls will be obtained for each of 300 expected cases: (1) a friend control for testing of the group B Coxsackievirus hypothesis by quantitation of IgM antibody to these agents in cases and controls; (2) a community control drawn by a random sample of the tartet area population for comparing other potential environmental exposures by means of a questionnaire interview. The ultimate goal of this proposed study is potential prevention of IDDM if particular environmental factors can be demonstrated to be important in disease development. A second important goal will be the generation of new information on possible pathogenetic mechanisms based on the interaction of genetic susceptibility with environmental exposure. Lastly, the study would provide the basis for the development of an IDDM registry in Southern Wisconsin with potential benefit for improving the education and care of such patients.